Electric heater.



No.' 842,849. PATBNTED FEB. 5, 19o?.

A. N. ANDERSON.

-FLBGTRIG HEATER.

APrLmATIoN FILED 11H31, 1905.

f- FOLJ? a .e fig Zmesses: 6lJ, Maf-d', A MQ...

ARTHUR N. ANDERSON, OF NIAGARA FALLS, NEW YORK.

ELEoTRlo HEATER.

No.l 842,849.

Specification of Letters Patent.

Patented Fei).V 5, 1907.

Applicationled May 31,1905. Serial No. 263,117.

To a/ZZ whom it may concern.-

Be it known that I, ARTHUR N. ANDERSON, a citizen of the United States, residing at Niagara Falls', in the county of Niagara and State of New York, have invented a new and useful Improvement in Electric Heaters, of which the following is a specification.

This invention relates to an electric heater in which the heat is developedvby conducting an electric current through a resistance or coil of wire.

-The objects in producing an improved heater ofy this character are to increase the efliciency of the heater and to reduce the cost of the same, to coniine the heat gener* ated and emitted to the desired surfaces, to prevent short-circuiting of the electric conductorwithin the heater, to avoid oxidation of theelectric' conductor, toprevent induc- 'tion' or waste currents, to prevent carbonization of the insulating material, and to improve the heater in other respects.

ln'the accompanying drawings, Figure l is a longitudinal sectional elevation of a sadiron constructed in accordance with my invention. Fi 2 is a top plan view of the body o'r shel of the sad-iron, showing the heating or resistance coil and the insulating strips therein preparatory to being covered. Fi 3 is a cross-section i-n line'3 3, Fig. 1.

Similar letters of reference indicate corresponding parts throughout the several views.

The external parts of the elec trically-heated flat or sad iron, shown in the drawings as one of the uses to which my invention is applica` ble, consists, essentially, of a hollow body or shell A, having a bottom a and an upright wall a around the margin of the bottom,'a cover B for closing the top of the shell, and a' handle O, secured to the upper side of the cover-by a screw c or otherwise.

In constructing m improved electric heater the shell or bo y of; the same is first lined on the inner vertical side of its walls with asbestos or other heat-insulating mate rial D. The bottom of the shell is a so covered with a protecting-sheet of mica d or similar waterproof non-plastic insulating material, so as to protect the bottom of the shell, which for economy is madeof iron, against. oxidation, which otherwise would be 'able\ to occur on account of the moisture in the material which Ais subsequently -placed in the shell above the mica protecting-sheet d.

The mica protecting-sheet also increases the effectiveness of the insulation and prevents shocks when an alternating current of high voltage is used, while at the same time serving as a good conductor of heat to the under side of the sad-iron. A comparatively thin lower plastic layer or filling cof siloxicon mixed with g psum or plaster-oi`paris in a moist or plastic condition is next placed over the mica d. After this plastic mass e is thoroughly dry an electric conductor or resist-ance member f is placed upon the same in the form of a coil which is doubled repeatedly upon itself in zigzag fashion, so as so forma plurality of coil-sections which are arranged parallel and transversely in the shell and connect with each other, so that the current flows through the same in series.

The electric conductor referably consists lof a wire made of an al oy of copper and mass h, composed of siloxicon an plaster-of paris or gypsum in dry powder form, is next placed over the coil-sections and the insulating-strips, so as to completely embed the same by entering the spaces between said parts and also covering the same. This layer is now moistened and gently packed, so that it is compact, and the same is then dried, forming a hard mass similar to that below the coil-sections and insulating-strips.

By lacing insulating-strips between the severaFsections of the resistance-coil before the upperembedding layer h is applied to the coil the sections of the latter are prevented from coming in contact with each otherbetween their ends, thus avoiding shortcircuiting of parts of the coil and preventing reduction of its eiiiciency.

In assembling the parts of the heater the several coil-sections of the resistance or conductor are liable to twist and s ring out of place, owing to the resilience oft e coils. In order to hold them in place, the opposite IOO 2 eee ends of the coil-sections are extended to the side walls of the shell, so as to-engage the same. The insulating-strips g are fitted tightly in the shell between the coil-sections, so that each strip bears closely on its opposite sides against the sides of the adjacent coil-sections and at its opposite ends against the inner sides of the shell and at one end against the connection between the respective coil-sections, whereby the several sections of the resistance or conductor are reliably held in place while the filling of electric insulating and heat-conducting material is bemg placed in the shell.

It has been found in practice that the heat is radiated from the edge or marginal part of the shell faster than from the central part thereof. In order to maintain the under side of the iron or other surface to be heated at a uniform temperature, the windin s of the resistance member are arranged c oser together at the margin or side of the shell than in the central part of the same. For this purpose several of the sections at the opposite ends or extremities of the coil have their windings all arranged close together, While each of the remaining intermediate sections have the windings at their opposite ends arranged close together and thoselin theircentral part spread or separated` af;-Ik

greater distance than their end windings, as

shown in Figs. 2 and 3. lt follows from this construction of the coil that the same when traversed by an electric current will develop more heat at the sides than in the center,

thus compensating for the difference in radiation and maintaining the heating-surface at a uniform temperature all over.

Siloxicon is the name of a composition made in accordance with United States Letters Patent Nos. 722,792, 722,793, and 787,869. This material when mixed with gy sum or plaster-of-paris as a bond for usev in *orming the lower and upperlayers e h produces a hard refractoryblock when dry which closely embeds the resistance member and is not liable to become carbonized or disintegrated under high temperatures. It further 1s perfectly Waterproof and a non-conductor of electricity, but has the capacity of holding a large volume of heat and readily transmitting or conducting the same. The electric conductor inclosed by this composition is therefore protected against the destructive action of moisture, air, or other elements which would have a corroding or oxidizing effect on the conductor and which are eectually excluded from the same, thereby insuring long life to the heater. Over the block which is thus formed and which has embedded therein the heating-coil a filling or layer i of asbestos is lplaced which extends of the shell with a non-conductor of heat and lacing a filling of like character over the iieatin -block containing the resistance the heat eveloped by the latter is prevented from., radiating upwardly and laterally and is confined to the surface on the under side of the shell where the same is required.

A layer or sheet y' of asbestos is preferably arranged between the under side of the cover and the top of the side walls a, the asbestos lining D, and asbestos filling i to prevent ltransmission of heat from the shell to the cover and handle of the heater. The cover and shell may be detachably connected in any suitable manner, the means for this purpose (shown in the drawings) consisting of screws k, which have only a small heat-conductingcapacity.

On the rear part of the handle the same is provided with a chamber L, which opens downwardly. Within this chamber an insulating-block M is secured to the top of the cover by a screw m or otherwise. This block is provided with two binding-screws n n, which receive the terminals of the heatingcoiland also the ends ofthe leading-in or current supply wires o o. The terminal wires extend from the extremities of the coil upwardly through coinciding openings or passages p p, formed in the asbestos layers i j; cover B, and insulating-block M. The leading-inwires-are inclosed by an insulating covering forming a cable, which passes through an opening g in the upper rear part of the handle-chamber, said cable being wrapped by aspring-coil g adjacent to the handle to prevent sharp bending of the same.

The chamber in the handle is preferably lled with asbestos r to insulate and also to prevent radiation of heat from the exposed electric conductors in the same.

I claim as my inventionl. An electric heater comprising a shell, a plurality of resistance coil-sections arranged parallel side by side in said shell, insulatingstrips arranged betweenl said sections and each strip bearing on its opposite sides against the sections between which the saine isarranged and at its opposite ends against the inner sides of the shell, and an electric insulating and heat-conducting filling arranged in the 'shell and completely embedding said coil-sections and strips, substantially as set forth.

2. An electric heater comprising a shell, a resistance composed of a plurality of coil-l sections arranged parallel side by side in said shell and bearing at opposite ends against y the opposite side walls of the shell and connected in series so as to form a'zigzag-shaped conductor, insulating-strips each arranged lengthwise between two adjacent coil-secflush to the topv of the shell, as shown in Figs. l and 3. By lming'the inner side of the waclls tionsand bearing on opposite sides against the sides of the coils which lit separates and lOO IIO

at Opposite ends against the side Walls Qf the Witness my hand this 27th day of May, shell and at one end against that portion of 1905. the resistance which connects the coil-sections on opposite sides ofthe same, and a ill- 5 ing arranged in'said shell and embedding said l Witnesses:

resistance and strip, substantially as set THEO. L. POPP, forth. E. M. GRAHAM.

ARTHUR N. ANDERSON. 

